<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    *{
        margin: 0;
        padding: 0;
        box-sizing: border-box;
    }
    body{
        height: 100vh;
        display: flex;
        justify-content: center;
        align-items: center;
        background-color: white;
    }
    .guang{
        position: relative;
        display: inline-block;
        width: 220px;
        height: 80px;
        color: rgb(255, 255, 255);
        line-height: 80px;
        font-size: 35px;
        font-family: sans-serif;
        text-decoration: none;
        text-transform: uppercase;
        text-align: center;
        border-radius: 30px;
        background: linear-gradient(90deg,rgb(39, 122, 218),rgb(74, 230, 121),rgb(201, 214, 13),rgb(226, 20, 233),rgb(16, 172, 219));
        background-size: 400%;
        z-index: 1;
        text-shadow: 0 0 5px white,
                     0 0 5px white;
    }
    .guang:hover{
        animation: move 5s linear alternate infinite;
    }
    @keyframes move{
        0%{
           background-position: 0%;
        }
        100%{
            background-position: 100%;
        }
    }
    .guang::before{
        content: '';
        position: absolute;
        top: -10px;
        left: -10px;
        width: 240px;
        height: 100px;
        background: linear-gradient(90deg,rgb(39, 122, 218),rgb(74, 230, 121),rgb(243, 169, 10),rgb(226, 20, 233),rgb(16, 172, 219));
        background-size: 400%;
        opacity: 0;
        z-index: -1;
        border-radius: 45px;
        transition: 0.6s;
       
    }
    .guang:hover::before{
        filter: blur(15px);
        opacity: 1;
        animation: move 8s linear alternate infinite;
    }
</style>
<body>
    <a href="#" class="guang">button</a>
</body>
</html>
